To investigate the relationship of the irradiance-beam-profile areas from six different light-curing units (LCUs) with the degree of conversion (DC), microhardness (KH), and cross-link density (CLD) throughout a resin-based composite (RBC) cured at two clinically relevant distances, and to explore the correlations among them.
Materials and methods
A mapping approach was used to measure DC using micro-Raman spectroscopy, KH using a Knoop indentor on a hardness tester, and %KH reduction after ethanol exposure, as an indicator for CLD within a nano-hybrid RBC increment (n = 3) at various depths. These sample composites were cured from two distances while maintaining the radiant exposure, using six different light-curing units: one quartz-tungsten-halogen; two single and three multiple-emission-peak light-emitting-diode units. Irradiance beam profiles were generated for each LCU at both distances, and localized irradiance values were calculated. Points across each depth were analyzed using repeated measures ANOVA. Correlations across multiple specimen locations and associations between beam uniformity corresponding with polymerization measurements were calculated using linear mixed models and Pearson correlation coefficients.
Significant non-uniform polymerization patterns occurred within the specimens at various locations and depths. At 2-mm curing distance, the localized DC = 52.7–76.8%, KH = 39.0–66.7 kg/mm2, and %KH reduction = 26.7–57.9%. At 8-mm curing distance, the localized DC = 50.4–78.6%, KH = 40.3–73.7 kg/mm2, and %KH reduction = 28.2–56.8%. The localized irradiance values were weakly correlated with the corresponding DC, KH, and %KH reduction, with only a few significant correlations (p < 0.05).
Although significant differences were observed at each depth within the specimens, the localized irradiance values for all LCUs did not reflect the polymerization pattern and did not seem to have a major influence on polymerization patterns within the RBC, regardless of the curing distance.
Commonly used LCUs do not produce uniform polymerization regardless of the curing distance, which may contribute to the risk of RBC fracture.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Demarco FF, Collares K, Coelho-de-Souza FH, Correa MB, Cenci MS, Moraes RR, Opdam NJ (2015) Anterior composite restorations: a systematic review on long-term survival and reasons for failure. Dent Mater 31:1214–1224. https://doi.org/10.1016/j.dental.2015.07.005
Alvanforoush N, Palamara J, Wong RH, Burrow MF (2017) Comparison between published clinical success of direct resin composite restorations in vital posterior teeth in 1995-2005 and 2006-2016 periods. Aust Dent J 62:132–145. https://doi.org/10.1111/adj.12487
Leprince JG, Palin WM, Hadis MA, Devaux J, Leloup G (2013) Progress in dimethacrylate-based dental composite technology and curing efficiency. Dent Mater 29:139–156. https://doi.org/10.1016/j.dental.2012.11.005
Ferracane JL (2013) Resin-based composite performance: are there some things we can’t predict? Dent Mater 29:51–58. https://doi.org/10.1016/j.dental.2012.06.013
Cramer NB, Stansbury JW, Bowman CN (2011) Recent advances and developments in composite dental restorative materials. J Dent Res 90:402–416. https://doi.org/10.1177/0022034510381263
Ferracane JL, Mitchem JC, Condon JR, Todd R (1997) Wear and marginal breakdown of composites with various degrees of cure. J Dent Res 76:1508–1516
Soh MS, Yap AU (2004) Influence of curing modes on crosslink density in polymer structures. J Dent 32:321–326. https://doi.org/10.1016/j.jdent.2004.01.012
Li J, Li H, Fok AS, Watts DC (2009) Multiple correlations of material parameters of light-cured dental composites. Dent Mater 25:829–836. https://doi.org/10.1016/j.dental.2009.03.011
Durner J, Obermaier J, Draenert M, Ilie N (2012) Correlation of the degree of conversion with the amount of elutable substances in nano-hybrid dental composites. Dent Mater 28:1146–1153. https://doi.org/10.1016/j.dental.2012.08.006
Santini A, Miletic V, Swift MD, Bradley M (2012) Degree of conversion and microhardness of TPO-containing resin-based composites cured by polywave and monowave LED units. J Dent 40:577–584. https://doi.org/10.1016/j.jdent.2012.03.007
Leprince JG, Leveque P, Nysten B, Gallez B, Devaux J, Leloup G (2012) New insight into the “depth of cure” of dimethacrylate-based dental composites. Dent Mater 28:512–520. https://doi.org/10.1016/j.dental.2011.12.004
Selig D, Haenel T, Hausnerova B, Moeginger B, Labrie D, Sullivan B, Price RB (2015) Examining exposure reciprocity in a resin based composite using high irradiance levels and real-time degree of conversion values. Dent Mater 31:583–593. https://doi.org/10.1016/j.dental.2015.02.010
Rencz A, Hickel R, Ilie N (2012) Curing efficiency of modern LED units. Clin Oral Investig 16:173–179. https://doi.org/10.1007/s00784-010-0498-3
Ilie N, Stark K (2014) Curing behaviour of high-viscosity bulk-fill composites. J Dent 42:977–985. https://doi.org/10.1016/j.jdent.2014.05.012
Schneider LF, Moraes RR, Cavalcante LM, Sinhoreti MA, Correr-Sobrinho L, Consani S (2008) Cross-link density evaluation through softening tests: effect of ethanol concentration. Dent Mater 24:199–203. https://doi.org/10.1016/j.dental.2007.03.010
Alshali RZ, Salim NA, Satterthwaite JD, Silikas N (2015) Post-irradiation hardness development, chemical softening, and thermal stability of bulk-fill and conventional resin-composites. J Dent 43:209–218. https://doi.org/10.1016/j.jdent.2014.12.004
Yap AU, Soh MS, Han TT, Siow KS (2004) Influence of curing lights and modes on cross-link density of dental composites. Oper Dent 29:410–415
Price RB, Ferracane JL, Shortall AC (2015) Light-curing units: a review of what we need to know. J Dent Res 94:1179–1186. https://doi.org/10.1177/0022034515594786
Rueggeberg FA (2011) State-of-the-art: dental photocuring--a review. Dent Mater 27:39–52. https://doi.org/10.1016/j.dental.2010.10.021
Rueggeberg FA, Giannini M, Arrais CAG, Price RBT (2017) Light curing in dentistry and clinical implications: a literature review. Braz Oral Res 31:e61. https://doi.org/10.1590/1807-3107BOR-2017.vol31.0061
Megremis SJ, Ong V, Lukic H, Shepelak H (2014) An ada laboratory evaluation of light-emitting diode curing units. J Am Dent Assoc 145:1164–1166. https://doi.org/10.14219/jada.2014.97
Jandt KD, Mills RW (2013) A brief history of LED photopolymerization. Dent Mater 29:605–617. https://doi.org/10.1016/j.dental.2013.02.003
Harlow JE, Sullivan B, Shortall AC, Labrie D, Price RB (2016) Characterizing the output settings of dental curing lights. J Dent 44:20–26. https://doi.org/10.1016/j.jdent.2015.10.019
Michaud PL, Price RB, Labrie D, Rueggeberg FA, Sullivan B (2014) Localised irradiance distribution found in dental light curing units. J Dent 42:129–139. https://doi.org/10.1016/j.jdent.2013.11.014
Price RB, Labrie D, Rueggeberg FA, Sullivan B, Kostylev I, Fahey J (2014) Correlation between the beam profile from a curing light and the microhardness of four resins. Dent Mater 30:1345–1357. https://doi.org/10.1016/j.dental.2014.10.001
Haenel T, Hausnerova B, Steinhaus J, Price RB, Sullivan B, Moeginger B (2015) Effect of the irradiance distribution from light curing units on the local micro-hardness of the surface of dental resins. Dent Mater 31:93–104. https://doi.org/10.1016/j.dental.2014.11.003
Price RB, Fahey J, Felix CM (2010) Knoop microhardness mapping used to compare the efficacy of LED, QTH and PAC curing lights. Oper Dent 35:58–68. https://doi.org/10.2341/09-055-L
Platt JA, Price RB (2014) Light curing explored in Halifax. Oper Dent 39:561–563. https://doi.org/10.2341/1559-2863-39.6.561
Price RB, Labrie D, Whalen JM, Felix CM (2011) Effect of distance on irradiance and beam homogeneity from 4 light-emitting diode curing units. J Can Dent Assoc 77:b9
Al-Zain AO, Eckert GJ, Lukic H, Megremis SJ, Platt JA (2018) Degree of conversion and cross-link density within a resin-matrix composite. J Biomed Mater Res B Appl Biomater 106:1496–1504. https://doi.org/10.1002/jbm.b.33960
Albino LG, Rodrigues JA, Kawano Y, Cassoni A (2011) Knoop microhardness and FT-Raman evaluation of composite resins: influence of opacity and photoactivation source. Braz Oral Res 25:267–273
Palin WM, Senyilmaz DP, Marquis PM, Shortall AC (2008) Cure width potential for MOD resin composite molar restorations. Dent Mater 24:1083–1094. https://doi.org/10.1016/j.dental.2008.01.001
Mousavinasab SM, Meyers I (2011) Comparison of depth of cure, hardness and heat generation of LED and high intensity QTH light sources. Eur J Dent 5:299–304
Beun S, Bailly C, Dabin A, Vreven J, Devaux J, Leloup G (2009) Rheological properties of experimental Bis-GMA/TEGDMA flowable resin composites with various macrofiller/microfiller ratio. Dent Mater 25:198–205. https://doi.org/10.1016/j.dental.2008.06.001
Leprince JG, Hadis M, Shortall AC, Ferracane JL, Devaux J, Leloup G, Palin WM (2011) Photoinitiator type and applicability of exposure reciprocity law in filled and unfilled photoactive resins. Dent Mater 27:157–164. https://doi.org/10.1016/j.dental.2010.09.011
Vasudeva G (2009) Monomer systems for dental composites and their future: a review. J Calif Dent Assoc 37:389–398
Watts DC, Cash AJ (1994) Analysis of optical transmission by 400-500 nm visible light into aesthetic dental biomaterials. J Dent 22:112–117
Ikemura K, Endo T (2010) A review of the development of radical photopolymerization initiators used for designing light-curing dental adhesives and resin composites. Dent Mater J 29:481–501
Vaidyanathan TK, Vaidyanathan J, Lizymol PP, Ariya S, Krishnan KV (2017) Study of visible light activated polymerization in BisGMA-TEGDMA monomers with type 1 and type 2 photoinitiators using Raman spectroscopy. Dent Mater 33:1–11. https://doi.org/10.1016/j.dental.2016.09.002
Sampaio CS, Atria PJ, Rueggeberg FA, Yamaguchi S, Giannini M, Coelho PG, Hirata R, Puppin-Rontani RM (2017) Effect of blue and violet light on polymerization shrinkage vectors of a CQ/TPO-containing composite. Dent Mater 33:796–804. https://doi.org/10.1016/j.dental.2017.04.010
Moore BK, Platt JA, Borges G, Chu TM, Katsilieri I (2008) Depth of cure of dental resin composites: ISO 4049 depth and microhardness of types of materials and shades. Oper Dent 33:408–412. https://doi.org/10.2341/07-104
Corciolani G, Vichi A, Davidson CL, Ferrari M (2008) The influence of tip geometry and distance on light-curing efficacy. Oper Dent 33:325–331. https://doi.org/10.2341/07-94
ISO (2007) 10650-2:2007 dentistry-powered polymerizationactivators: part 2: light-emitting diode (LED) lamps. Geneva,Switzerland: International Standards Organization.:7
Harlow JE, Rueggeberg FA, Labrie D, Sullivan B, Price RB (2016) Transmission of violet and blue light through conventional (layered) and bulk cured resin-based composites. J Dent 53:44–50. https://doi.org/10.1016/j.jdent.2016.06.007
Shimokawa C, Sullivan B, Turbino ML, Soares CJ, Price RB (2017) Influence of emission spectrum and irradiance on light curing of resin-based composites. Oper Dent 42:537–547. https://doi.org/10.2341/16-349-L
The work is part of the PhD dissertation for Dr. A. O. Al-Zain. The scholarship support from King Abdulaziz University, Jeddah, Saudi Arabia, and the technical assistance received from UITS/PTI Advanced Visualization Lab at Indiana University are acknowledged.
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
For this type of study, formal consent is not required.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Al-Zain, A.O., Eckert, G.J., Lukic, H. et al. Polymerization pattern characterization within a resin-based composite cured using different curing units at two distances. Clin Oral Invest 23, 3995–4010 (2019). https://doi.org/10.1007/s00784-019-02831-1
- Degree of conversion
- Cross-link density
- Resin composite
- Beam profile
- Light-curing unit